The small town of
Cherryfield, Maine, is in Washington County, in the southeastern
corner of the state. It is located on the Narraguagus River,
approximately six miles above its confluence with the sea. This
locality was well-known to diatomists of the 19th Century
as a source of fossil diatoms, as attested by the numerous antique
microscope slides that bear the Cherryfield name on their labels.
Several other localities in Maine, such as Beddington, Jonesport,
Monmouth, and Orono River, were also known as sources of fossil
diatoms, but slides from Cherryfield are definitely more abundant in
today’s antique slide market. For those like myself, lacking
access to a good research library, it is surprisingly difficult to
locate any information on the nature of these deposits, however.
Slides from several of these Maine localities, including Cherryfield,
were among those offered by Tempère and Peragallo in their
Diatomées du Monde Entier collection, where they were
identified as being fossil freshwater deposits. Patrick and Reimer
(1966:389) cited Cherryfield as the type locality for Neidium
tumescens (Grunow in Schmidt) Cleve, described in 1877. Until
this past year, that constituted the full extent of my knowledge of
this locality.

About a year ago I had
the opportunity to purchase two slides from an old Cherryfield
sample, mounted by Robert I. Firth in April, 1970. I bought the
slides, and have been fascinated by them ever since. The two slides
are a bit different, in that one is labeled “large” and
the other is labeled “small”; Firth obviously split the
sample into two size fractions. The fascination of these slides
derives from what they contain, obviously. Having worked a lot with
samples of both recent and fossil diatoms from the American Prairies,
Great Plains, and Southwest, I was startled by the Cherryfield
slides, not only by the suite of species to be seen, but also by what
they seem to “lack”. Fossil freshwater diatoms typically
accumulate in lake sediments, and one expects to see the full gamut
of lacustrine environments represented: planktonic forms, epiphytic
forms, epipelic forms, etc. Cherryfield diatoms are different!

First, there are no
centric diatoms at all. The Stephanodiscus, Cyclotella, and
Aulacoseira species that the Midwesterner expects to find are
simply not there. No planktonic pennate forms are to be found,
either; no Asterionella, no Fragilaria, no Synedra.
The usual plethora of such epiphytes as Cocconeis, Epithemia,
and Rhopalodia are also not to be seen. Epipelic forms like
Gyrosigma and Nitzschia are lacking. Navicula and
Caloneis species are quite rare (with one exception, see
below). There are few species of Cymbella and Encyonema,
although the species that are present may be fairly common.
So, what does that leave, you might ask?

I have thus far
identified 64 taxa of diatoms on these two slides, among which are 17
taxa of Eunotia, 16 Pinnularia, 7 Neidium, 4
Brachysira, 3 Frustulia, and 2 Stenopterobia,
plus the “telltale” species Actinella punctata Lewis.
What the majority of these taxa have in common is a set of
ecological preferences not commonly encountered in the American
Midwest or Great Plains: they prefer water with a low pH and low
conductance, and a high percentage of dissolved humates. They are
primarily calciophobic, and sphagnophiles. (Cf. Patrick and Reimer
1966:42, 48.) We seem to be looking at diatoms that accumulated in a
bog!1

The age of the deposit
is most probably Holocene, since bogs in the northern United States
commonly developed in terrain formerly covered by glaciers –
often in glacial kettles, where large blocks of stagnant ice melted
to form relatively shallow, water-filled depressions. This cool,
shallow-water environment would be invaded by Sphagnum mosses,
whose accumulation would begin to produce the acidic, dystrophic
conditions that this diatom community so clearly reveals.2

Figure 1.

Figure 1 shows Neidium
tumescens (Grunow in Schmidt) Cleve. As mentioned above,
Cherryfield is the type locality for this taxon, and it is fairly
common there. Figures 2 and 3 show N. affine (Ehrenberg)
Pfitzer and N. bisulcatum (Lagerstedt) Cleve, species that are
fairly cosmopolitan in low-pH environments.

Figure 2.

Figure 3.

Of perhaps more
interest are two Neidium species that are endemic to the
northeastern quadrant of North America, N. boyeri Reimer and
N. temperei Reimer, Figures 4 and 5. The latter species is
one of the group in which the proximal raphe ends are straight,
rather than being hooked in opposite directions, as seen in the great
majority of the commoner Neidium species.

Figure 4.

Figure5.

The only common member
of the genus Navicula at Cherryfield is the curious N.
monmouthiana-stodderi Yermoloff, so-named because it was thought
to form an evolutionary “bridge” between N.
monmouthiana Grunow in Cleve and Grunow, and Encyonopsis
stodderi (Cleve) Krammer. Figure 6 shows this species, which
does indeed look like an Encyonopsis. Although first
mentioned and figured by Yermoloff in a very curious paper in 1918
(Yermoloff 1918: 418, Plate 27, figs. 3-4), valid publication of the
taxon was not achieved until it was more fully described in Zanon
1930, according to the diatom names database at the California
Academy of Sciences.3

Figure 6.

Figures 7, 8, and 9
show three species of Brachysira that are common at
Cherryfield, all notably acidophiles. (The fourth Brachysira
species common at Cherryfield, B. vitrea (Grunow) R. Ross,
is apparently pH indifferent.) Note the prominent “Voigt
faults” in these species, a character that they share with most
species of Neidium.

Figure 7.

Figure 8.

Figure 9.

The three species of
Frustulia are clearly distinct, although I cannot put a name
to the one I am calling Frustulia sp. A. The size ranges of
these species do not overlap, and each has a characteristic valve
outline. Frustulia sp. A is additionally distinguished by its
lack of the porte-crayon, the typical “pencil point” that
appears at the distal raphe ends of most members of this genus.
Figures 10, 11, and 12 illustrate each of these taxa.

Figure 10.

Figure 11.

Figure 12.

Figure 13 shows
Actinella punctata Lewis, a species well-known for its
preference for dystrophic water and bog environments. It occurs
widely, in proper conditions, in eastern North America, and is also
known from northern Europe.

Figure 13.

Members of the genus
Eunotia are illustrated in Figures 14 through 18. Figure 16
shows E. hemicyclus (Ehrenberg) Ralfs in Pritchard, a species
that has been shuffled about through a number of different genera
because of an earlier belief that it was an araphid. The discovery
that it does, in fact, possess a raphe has cleared the way for its
proper inclusion in Eunotia.

Figure 14.

Figure 15.

Figure 16.

Figure 17.

Figure 18.

The genus Stauroneis
is represented by two taxa, S. phoenicenteron (Nitzsch)
Ehrenberg and S. phoenicenteron f. gracilis (Ehrenberg)
Hustedt. Although the former is seemingly pH indifferent, the latter
form, illustrated in Figure 19, is an acidophile.

Figure 19.

The surirellacean genus
Stenopterobia has few species, and all prefer dystrophic
water. Two species (Figures 20 and 21) are found at Cherryfield, the
North American endemic S. anceps (Lewis) Brébisson ex
Van Heurck, and the more widely distributed S. sigmatella
(Gregory) R. Ross in Hartley.4

Figure 20.

Figure 21.

To show the acidophilic
nature of this diatom community, I have constructed the following
table, based on data from Table 5 in Camburn and Charles (2000:
139-143). This table shows the pH preference of various diatom
species found at Cherryfield, in terms of their Abundance Weighted
Means (AWM) and standard deviations (SD) in the low-alkalinity lakes
of the PIRLA project, from Adirondack Park in northern New York.

It is interesting to
note that the nominate form of Stauroneis phoenicenteron, in
contrast to the form gracilis, has a pH AWM of 6.57 with a SD
of 0.78, making it essentially circumneutral.

Comments
to the author,
Richard Carter, would be most welcome!In addition, should anyone care to see
a full list of the diatoms I have identified from Cherryfield, I can
easily provide one through an e-mail attachment.

Notes

1. Not meaning the bog
of an English or Irish pub; the waters of those environments tend
more toward the alkaline……

2. I have collected a
somewhat similar suite of diatoms from a current Sphagnum bog
near the headwaters of Rapid Creek in the northern Black Hills of
South Dakota. That bog is a bit different, in that it formed on a
small flat area on a spring-fed, wet alpine slope in Ponderosa Pine
forest.

3. The 1918 Yermoloff
paper, with its rather peculiar understanding of Darwinian evolution,
remarks on the destruction of Atlantis, analogies between
mathematical calculus and biological taxonomy, etc., makes very
entertaining reading! It is interesting, however, that Yermoloff
recognized clearly the taxonomic unity of many of the forms that have
been recently transferred to the new genus Encyonopsis.

4. A junior synonym of
the latter is S. curvula (W. Smith) Krammer.

References

Camburn, Keith E. and
Donald F. Charles, 2000, Diatoms of Low-alkalinity Lakes in the
Northeastern United States, The Academy of Natural Sciences of
Philadelphia, Special Publication 18.

Patrick, Ruth and
Charles W. Reimer, 1966, The Diatoms of the United States
(Exclusive of Alaska and Hawaii), Volume 1, The Academy of
Natural Sciences of Philadelphia, Monograph 13.